Since the introduction of 800 MHz band cellular communications in the early 1980's, wireless communication service has grown rapidly. During this same period, Enhanced 9-1-1 (E911) has proliferated the U.S. wired communication system, thereby providing accurate location of 9-1-1 wired callers, among other things, such as routing 9-1-1 calls to appropriate emergency dispatch centers. To provide a level of service comparable to E911 in wireless communication system, location systems have been developed to locate mobile-telephones. However, prior art location systems are deficient for a number of reasons.
First, the prior art location systems typically exist independently of the wireless communication systems, i.e., non-integrated with the wireless communication systems, thereby increasing the cost of location systems although some of the equipment and information used and collected by the location systems and the wireless communication systems are the same.
Second, the prior art location systems can only locate mobile-telephones within the geographical area covered by the location system. Thus, if the mobile-telephone is not within the coverage area of the location system, or if the person desiring to locate the mobile-telephone does not know the general area or identity of the location system in which the mobile-telephone is located, then the mobile-telephone cannot be located.
Third, the prior art location systems typically monitors overhead channels for transmissions containing 9-1-1 phone numbers or some other predetermined phone number or sequence of characters. Because of prohibitively high costs, the prior art location systems do not monitor voice channels. Consequently, the capability of the prior art systems are limited, e.g., cannot locate mobile-telephones that are idle or engaged in a conversation.
Accordingly, there exist a need for an inexpensive location system that is integrated into a wireless communication system and is operable to locate mobile-telephones within the geographical area covered by the current location system or another location system. There further exist a need for a location system that can locate a mobile-telephone in a multitude of call states.